Improving Morphological Quality and Uniformity of Hydrothermally Grown ZnO Nanowires by Surface Activation of Catalyst Layer

Murillo, Gonzalo,Lozano, Helena,Cases-Utrera, Joana,Lee, Minbaek,Esteve, Jaume Springer US 2017 NANOSCALE RESEARCH LETTERS Vol.12 No.1

<P>This paper presents a study about the dependence of the hydrothermal growth of ZnO nanowires (NWs) with the passivation level of the active surface of the Au catalyst layer. The hydrothermal method has many potential applications because of its low processing temperature, feasibility, and low cost. However, when a gold thin film is utilized as the seed material, the grown NWs often lack morphological homogeneity; their distribution is not uniform and the reproducibility of the growth is low. We hypothesize that the state or condition of the active surface of the Au catalyst layer has a critical effect on the uniformity of the NWs. Inspired by traditional electrochemistry experiments, in which Au electrodes are typically activated before the measurements, we demonstrate that such activation is a simple way to effectively assist and enhance NW growth. In addition, several cleaning processes are examined to find one that yields NWs with optimal quality, density, and vertical alignment. We find cyclic voltammetry measurements to be a reliable indicator of the seed-layer quality for subsequent NW growth. Therefore, we propose the use of this technique as a standard procedure prior to the hydrothermal synthesis of ZnO NWs to control the growth reproducibility and to allow high-yield wafer-level processing.</P><P><B>Electronic supplementary material</B></P><P>The online version of this article (doi:10.1186/s11671-017-1838-x) contains supplementary material, which is available to authorized users.</P>

Mechanical and electrical characterization of PVDF-ZnO hybrid structure for application to nanogenerator

Choi, Moonkang,Murillo, Gonzalo,Hwang, Sungmin,Kim, Jae Woong,Jung, Jong Hoon,Chen, Chih-Yen,Lee, Minbaek Elsevier 2017 Nano energy Vol.33 No.-

<P><B>Abstract</B></P> <P>The hybridization of different nanomaterials has been studied widely for the versatile use of nanogenerators in a range of environments. This paper reports an analysis of the power enhancements in a hybrid piezoelectric structure comprised of zinc oxide (ZnO) nanowires and poly(vinylidene fluoride) (PVDF) polymer. The mechanical properties were examined by atomic force microscopy and simulated by the finite element method. The electrical properties of the hybrid nanogenerators were observed by electrostatic force microscopy and direct I-V measurements. Based on this analysis, the ZnO nanowires delivered internal strain to the PVDF in the hybrid structure, which enhanced the electrical power output of a hybrid nanogenerator. These results may open up new ways to optimize a hybrid piezoelectric structure in terms of its design and the spatial arrangement of each nanostructure.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The origin of the power enhancement in a composite nanogenerator comprised of ZnO nanowires and PVDF is investigated. </LI> <LI> Electrostatic force microscopy measurements confirm major contribution of power outputs in a hybrid structure. </LI> <LI> Quantitative analysis of mechanical properties of a hybrid structure exhibits a transferring local strains. </LI> <LI> Finite element method simulation supports the experimental results regarding the origin of power enhancement in a hybrid nanogenerator. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Preoperative neutrophil-to-lymphocyte ratio is prognostic for early recurrence after curative intrahepatic cholangiocarcinoma resection

Woo Jin Choi,Fiorella Murillo Perez,Annabel Gravely,Tommy Ivanics,Marco P. A. W. Claasen,Liza Abraham,Phillipe Abreu,Robin Visser,Steven Gallinger,Bettina E. Hansen,Gonzalo Sapisochin 한국간담췌외과학회 2023 Annals of hepato-biliary-pancreatic surgery Vol.27 No.2

Interdigital electrode based triboelectric nanogenerator for effective energy harvesting from water

Kil Yun, Byung,Soo Kim, Hyun,Joon Ko, Young,Murillo, Gonzalo,Hoon Jung, Jong Elsevier 2017 Nano energy Vol.36 No.-

<P><B>Abstract</B></P> <P>Despite high voltage output, the low current output of triboelectric nanogenerators (TENGs) limits their expansion into practical applications. The incorporation of additional machinery, such as transformers and gear trains, has been proposed to remove this bottleneck. Here, we report a simple and cost-effective strategy that employs a compact interdigital electrode (IDE) to increase the current output in TENG devices. A foldable, twistable, and rollable IDE-based TENG, comprised of finger-like aluminum electrodes sandwiched between polytetrafluoroethylene and polyester films, was fabricated to harvest triboelectric energy from water. This IDE-based TENG exhibited a triboelectric charge threefold higher than that of a single electrode-based TENG. Triboelectric charge is greatly enhanced when the width of the IDE is comparable to the size of the water droplet being harvested. Using a cone-shaped IDE-based TENG, we showed that the folding angle of the device and the water droplet volume rate are important for enhancing triboelectric currents. Using a cylinder-shaped IDE-based TENG, we demonstrated the powering of 10 light emitting diodes and the charging of a 0.1-μF capacitor to 15V within 20s.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Sharp increase of triboelectric current in interdigital electrode based triboelectric nanogenerators. </LI> <LI> Large degrees of freedom in interdigital electrode to harvest triboelectric energy of water. </LI> <LI> Reliable and durable device structure for various kinds of water at diverse places. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Electrically Enhanced Readout System for a High-Frequency CMOS-MEMS Resonator

Arantxa Uranga,Joan Lluis Lopez,Jordi Teva,Francesc Torres,Joan Josep Giner,Gonzalo Murillo,Gabriel Abadal,Nuria Barniol,Jaume Verd 한국전자통신연구원 2009 ETRI Journal Vol.31 No.4

The design of a CMOS clamped-clamped beam resonator along with a full custom integrated differential amplifier, monolithically fabricated with a commercial 0.35 m CMOS technology, is presented. The implemented amplifier, which minimizes the negative effect of the parasitic capacitance, enhances the electrical MEMS characterization, obtaining a 48×108 resonant frequency-quality factor product (Q×fres) in air conditions, which is quite competitive in comparison with existing CMOS-MEMS resonators.

Floating buoy-based triboelectric nanogenerator for an effective vibrational energy harvesting from irregular and random water waves in wild sea

Kim, Dong Yeong,Kim, Hyun Soo,Kong, Dae Sol,Choi, Moonkang,Kim, Hak Bum,Lee, Jae-Hyoung,Murillo, Gonzalo,Lee, Minbaek,Kim, Sang Sub,Jung, Jong Hoon Elsevier 2018 Nano energy Vol.45 No.-

<P><B>Abstract</B></P> <P>Water waves in wild sea have unique characteristics of being huge, random, irregular, and of low frequency. To effectively harvest such vibrational energy, any devices should be light enough to float, sensitive even to small amplitudes, durable against harsh environmental conditions, easily replaceable after long-term use, and easily linked to form a network. Here, a floating buoy-based triboelectric nanogenerator (FB-TENG) is demonstrated to effectively harvest the vibrational energy with full satisfaction of these requirements. The FB-TENG consisted simply of a power generation unit, which was packed in an acrylic case, and a height-adjustable support, which was attached to a floating buoy. Even for the small amplitude of water waves, the height-adjustable support provides vigorous vibration at the power generation unit; which was sufficient to power 30 light-emitting diodes (LEDs), and operate a digital thermo-hygrometer and an anenometer. Under saltwater (salinity of 40%), thermal shocks (temperature range of 4–60°C), and strong ultraviolet irradiation (power of 10 W), the FB-TENG generates stable electric power by virtue of the acrylic packing of the power generation units. The FB-TENG also generates electric power from the various and mixed amplitudes and frequencies of water waves coming from all directions. Furthermore, the FB-TENG can easily be integrated into a network for high-power generation. This work provides a significant step forward in the harvesting of the blue energy of water waves, and the realization of self-powered sea mark and weather monitoring systems in wild sea.</P> <P><B>Highlights</B></P> <P> <UL> <LI> High power generation for small amplitude of water waves coming from all directions. </LI> <LI> Simple and safe Ar-plasma etching for the enhanced triboelectrification of PTFE. </LI> <LI> Strong resistance against harsh environmental conditions of wild sea. </LI> <LI> Self-powering of light emitting diodes, thermo-hygrometer, and anemometer. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>